Electrical Engineering ⇒ Topic : Applications of Series Circuits

Applications of Series Circuits

Series circuits are commonly seen in applications, such as street lamps, and airport runway lamps. Another example of an every day occurrence is lighting at temples and houses during festivals and decoration of Christmas trees. When one of the lamps in the string burns out, all the bulbs do not glow because the circuit is no longer complete for the current flow. The fused bulbs is an open circuit for current flow. If a string contains 10 bulbs and if it is connected to a 200 V source,20 V will appear across each bulb. If one bulb burns out then 200 V will appear across the remaining 9 bulbs, and 22.2 V will appear across each bulb. This increased voltage can burn out another bulb and so on. In the case of airport runway lamps and street lamps, normally constant current-variable voltage sources are used to avoid burning of bulbs and to maintain continuous illumination. When one of the bulbs burns out, a device at the lamp automatically short circuits the defective lamp, thus allowing other bulbs to glow continuously. The variable voltage source will automatically reduce the voltage across the circuit reducing the current flow through the lamps (normal rated current is maintained) thus preventing further burning out of lamps